This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Current screening methods for metabolic diseases are too costly, expensive, and time-consuming for broadly testing all newborns. Thus, many metabolic diseases go undetected and untreated for many years and screening is implemented only for the one most common metabolic disease. Using the proposed sol-gel supported aptamer-dye mix-and-measure assays in urine allows for cost-effective mass screening. The roposed research is dedicated to the development of new, highly selective, and sensitive molecular sensors that change color or fluorescence properties in the presence of steroid metabolites. Several steroids are disease markers for inborn metabolic diseases. We are interested in mapping three-way junctions of oligonucleotide-based binders (aptamers) to determine general principles that can be used in understanding molecular recognition of fluorescent dyes, visible dyes, steroids, and their metabolites by aptamers. The screening of aptamer-dye complexes will address an important medical need by generating cost-effective, rapid, mix-and-measure methods suitable for mass screening and monitoring of steroids or metabolites caused by faulty steroid metabolism. Organic dyes that form strong complexes with binding aptamers and metabolites will be found using a combinatorial 96-well plate approach. Reliable aptamer binding assays by UV-Vis and fluorescence spectroscopy have been established by our group. Furthermore, aptamers will be incorporated into colloidal silicate polymers for the development of handheld solid sensor devices to be used in medicinal applications. "Sol-gels" are based on solid colloidal silicates that will form a porous hard gel and will incorporate the aptamer-dye complexes within the gel, allowing for attaching the new molecular sensors into a solid support.[unreadable][unreadable]